The present invention relates to a method and apparatus for drying pulverous, granular or chip formed material such as bark, in which method and apparatus drying is effected by introducing drying gas through a bed formed of the material to be dried on an endless, moving wire.
Conventionally, drying of such materials is effected by means of a conveyor belt permeable to gas. Drying gas is blown through the conveyor belt from below and the material to be dried is fed to the front part of the belt and discharged from the rear end. Having regard to energy consumption and the drying process, such drying method is not optimal.
The object of the present invention is to provide an improved method and apparatus for drying particulate material.
The method of the present invention is mainly characterized in that a material to be dried forms a circulating bed, one side of which, i.e., where the through-flowing drying gas is discharged, is continuously supplied with material to be dried and the other side of which bed, i.e., where the drying gas is introduced, has a corresponding amount of dried material continuously discharged therefrom.
The apparatus of the present invention is characterized in that it comprises first, second, and third wire loop sections, each with a wire turning roll and a wire guide roll. The section supporting the bed of the second wire loop is disposed after the section supporting the bed of the first wire loop, in the direction of movement of the materials. There is an opening between the first and second sections supporting the bed. The wire of the third wire loop is guided via the outer wire turning roll of the second wire loop, below the first and second wire loops, further to the utmost wire turning roll of the first wire loop, and runs partly around the wire turning rolls along with the material. The material thus lies between the second and third wires and between the first and third wires. The feed means is disposed in the substantially straight, preferably horizontal, front end of the dryer section of the first wire loop, and the discharge means is arranged in the opening between the sections of the first and second wire loops, which sections support the bed.
The present invention will be further described in greater detail, with reference to the accompanying drawings, which illustrate an example of implementation of the invention.